Local Charge Density Enhancement Strategy in Nitrogen-rich Covalent Organic Framework for Boosted Iodine Removal From...

The leakage of nuclear pollution highlights the critical importance of effectively separating radioactive pollutants. Radioactive iodine, a high-yield fission product of nuclear reactions, poses serious environmental and health risks. However, the lack of efficient adsorbents makes the management of aqueous radioactive iodine pollution a significant challenge. N-doped materials are among the most recognized adsorbents for iodine removal, but their weak binding affinity and limited number of iodine-binding N-sites hinder their practical application. Herein, a covalent organic framework (COFs) named phen-TPA is synthesized, featuring an increased number and optimized local chemical environment of iodine-binding N-sites. This material demonstrates record-breaking iodine removal kinetics, with a kinetic constant of 14.64 g g^-1 min^-1 for aqueous iodine (I₂), and the highest-reported iodine adsorption capacity of 11.9 g g^-1 for aqueous triiodide (I₃ ^-). Large-scale flow-through adsorption experiments show that phen-TPA can remove 99.5% aqueous I₂ and I₃ ^- from high-salinity aqueous environments, highlighting its potential for practical applications.